1. Field of the Invention
The present invention relates to a slider producing method, and, more particularly, to a slider producing method in which the surface of a slider where an end of a recording/reproducing thin-film element is exposed is lapped.
2. Description of the Related Art
FIG. 5 illustrates a wafer and a slider bar cut out from the wafer, in a conventional slider producing method. FIG. 6 is a sectional view of the main portion of the wafer illustrated in FIG. 5. FIG. 7 is a perspective view showing in enlarged form the main portion of the slider bar illustrated in FIG. 5. FIGS. 8A and 8B are used to illustrate the lapping process in the conventional slider producing method. More specifically, FIG. 8A schematically illustrates a lapping machine used in the lapping process, and FIG. 8B is a sectional view of FIG. 8A. FIG. 9 is used to illustrate the main steps of the lapping process, in the conventional slider producing method. FIG. 10 is a perspective view of a slider, in the conventional slider producing method. FIG. 11 is a perspective view of a slider, which has been lapped using the conventional slider producing method. FIG. 12 is a plan view showing in enlarged form the main portion of the slider illustrated in FIG. 11.
In magnetic heads used in, for example, hard disk devices, a slider, primarily formed of a ceramic material, is mounted to an end of a supporting member, formed of a leaf spring material.
A description will now be given of a conventional slider producing method. Referring to FIG. 5, a plurality of recording/reproducing thin-film elements 1 are formed in rows so as to form a pattern on a disk-shaped wafer W formed of, for example, alumina-titanium carbide (Al.sub.2 O.sub.3 --TiC) ceramic. Each thin-film element 1 comprises a reproducing head, for reproducing magnetic signals recorded on a magnetic recording medium, and a recording head, for recording magnetic signals onto a magnetic recording medium. Each reproducing head comprises a magnetoresistive (MR) head portion 1a formed by a magnetoresistive effect element portion. Each recording head comprises an inductive head portion 1b formed of a coil and a core, which are formed into a pattern.
As shown in FIG. 6, each MR head portion 1a comprises a lower shield layer 1a1 placed on top of a wafer W and formed of Ni--Fe alloy (permalloy); a lower gap layer 1a2 placed on top of the lower shield layer 1a1 and formed of a nonmagnetic material such as Al.sub.2 O.sub.3 ; a magnetoresistive effect element portion 1a3 formed at the center of the layer above the lower gap layer 1a2; hard bias layer 1a4, being a vertical bias layer, formed on both sides of the magnetoresistive effect element portion 1a3; an electrically conductive layer 1a5 formed on top of the hard bias layer 1a4 (formed on both sides of the magnetoresistive effect element portion 1a3) and formed of a nonmagnetic, electrically conductive material, such as chromium (Cr); an upper gap layer 1a6 formed on top of the magnetoresistive effect element portion 1a3 and the electrically conductive layer 1a5, and formed of a nonmagnetic material such as Al.sub.2 O.sub.3 ; and an upper shield layer 1a7 formed on top of the upper gap layer 1a6 and formed of Ni--Fe alloy (permalloy).
Each inductive head portion 1b comprises a lower core 1b1 also serving as the upper shield layer 1a7 of the MR head portion 1a; a nonmagnetic material layer 1b2 formed on top of the lower core 1b; and an upper core 1b3 formed so as to contact part of the nonmagnetic material layer 1b2. A protective film 1c, formed of Al.sub.2 O.sub.3 or the like, covers the upper core 1b3 and the side of a base 2 where its associated thin-film element is formed. An insulating material (not shown) is placed on top of the nonmagnetic material layer 1b2. A spirally formed coil (not shown), formed of a low resistance, electrically conductive material (such as copper (Cu)), is embedded in the insulating material (not shown).
With the plurality of thin-film elements arranged in rows, a plurality of rectangular shaped portions are cut out from the wafer W to obtain slider bars B. As shown in FIG. 6, an end portion (or magnetic gap portion) of the MR head portion 1a and the inductive head portion 1b of each of the aforementioned thin-film elements 1 are exposed at the sectioned surface of the corresponding slider bars B.
With the slider bars B formed, the surface of each slider bar B where the magnetic gap portions of each thin-film element 1 are exposed is lapped. Each slider bar B is given a crown shape so that its center portion bulges upward, whereby each slider bar B has a spherically curved structure. Each slider bar B is lapped by a lapping machine. As shown in FIG. 8A, a lapping machine comprises a substantially circular cylindrical lapping table formed of tin (Sn), and a mounting jig 52 disposed above the lapping table 51. The lapping table 51 comprises a lapping surface 51a, from which parts of diamond grains (not shown) embedded therein are exposed, and, as shown in FIG. 8B, a plurality of concentrically formed grooves 51b provided in the lapping surface 51a. The lapping surface 51a is a spherically curved surface and a circular arc shaped recess. The mounting surface 52a of the mounting jig 52, to which each of the slider bars B is mounted, is a convex-shaped surface formed in correspondence with the spherically curved shape of the lapping surface 11a and so as to oppose the lapping surface 51a.
The plurality of slider bars B are mounted to the convex-shaped mounting surface 52a of the mounting jig 52 with a resilient adhesive material so as to be bent in the longitudinal direction thereof and along the convex-shaped mounting surface 52a. As shown in FIG. 9, the slider bars B are disposed in the longitudinal directions thereof, and in the direction of rotation of the mounting surface 52a. The surface of each slider bar B where the magnetic gap portions of each thin-film element are exposed is disposed so that it can come into contact with the lapping surface 51a of the lapping table 51. A load is applied to the mounting jig 52 from thereabove, causing each of the slider bars B to be pressed against the lapping surface 51a. As shown in FIG. 6, each of the slider bars B is lapped by rotating the lapping table 51 at a proper speed, and by rotating the mounting jig 52, to which the slider bars B are mounted, while supplying a lubricant to the lapping surface 51a. Excess lubricant or diamond grains, which have come off the lapping surface 11a, fall into the grooves 51b. (This is not illustrated.)
Each of the slider bars B (given a crown shape by lapping) is formed into a predetermined shape by, for example, a photolithography process or ion milling, and is divided to form a plurality of sliders S. As shown in FIG. 10, each slider S comprises a substantially rectangular parallelepiped base 2 formed of, for example, alumina-titanium carbide (Al.sub.2 O.sub.3 --TiC) ceramic; an air groove 3 formed in its associated base 2; rails 4 and 4 formed on both sides of its associated air groove 3; a thin-film element 1 formed on a side end face of its associated base 2; and inclined portions 5 and 5 formed on its associated base 2 or at the side of the corresponding rails 4 and 4 opposite to the side where its associated thin-film element 1 is formed. The magnetic gap portion of each MR head portion 1a and the magnetic gap portion of each inductive head portion 1b are exposed at the top surface of one of the rails 4 of their associated slider S. The surface of each slider S where the magnetic gap portions are exposed constitutes an air bearing surface (ABS), or floating surface, which faces a magnetic recording medium. Each rail 4 has a crown shape C whose center portion bulges slightly upward, whereby each rail 4 has a spherically curved structure. Accordingly, the sliders S are obtained.